U.S. patent number 9,426,704 [Application Number 14/673,001] was granted by the patent office on 2016-08-23 for apparatus and method for managing an access mode of a node b in a wireless communication system.
This patent grant is currently assigned to Samsung Electronics Co., Ltd. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Yung-Soo Kim, Ok-Seon Lee.
United States Patent |
9,426,704 |
Lee , et al. |
August 23, 2016 |
Apparatus and method for managing an access mode of a node B in a
wireless communication system
Abstract
An apparatus and a method for managing an access mode of an NB
in a wireless communication system. The method includes receiving,
from a first NB, a request to change the access mode of the second
NB from a first mode into a second mode; determining, by the CN, to
change the access mode of the second NB into the second mode;
transmitting, to the second NB, a request message requesting to
change the access mode of the second NB; and receiving, from the
second NB, a response message informing of an access mode control
result. If the first mode allows access only to terminals having a
registration in the second NB, and the second mode allows access to
terminals, the second NB further grants access to at least one
terminal not registered in the second NB, after changing the access
mode.
Inventors: |
Lee; Ok-Seon (Gyeonggi-do,
KR), Kim; Yung-Soo (Gyeonggi-do, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Gyeonggi-do |
N/A |
KR |
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Assignee: |
Samsung Electronics Co., Ltd
(KR)
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Family
ID: |
43300665 |
Appl.
No.: |
14/673,001 |
Filed: |
March 30, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150208294 A1 |
Jul 23, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12797271 |
Jun 9, 2010 |
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Foreign Application Priority Data
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Jun 9, 2009 [KR] |
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10-2009-0051131 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
48/16 (20130101); H04W 36/22 (20130101); H04W
36/0061 (20130101); H04W 60/04 (20130101); H04W
36/0077 (20130101); H04W 48/08 (20130101); H04W
84/045 (20130101); H04W 88/10 (20130101) |
Current International
Class: |
H04W
36/00 (20090101); H04W 60/04 (20090101); H04W
48/16 (20090101); H04W 36/30 (20090101); H04W
36/22 (20090101); H04W 84/04 (20090101); H04W
88/10 (20090101); H04W 48/08 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 973 365 |
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Sep 2008 |
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EP |
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10-2009-0024861 |
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Mar 2009 |
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KR |
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WO 2007/086679 |
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Aug 2007 |
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WO |
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WO 2008/096162 |
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Aug 2008 |
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WO |
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Other References
Korean Office Action dated Sep. 18, 2015 issued in counterpart
Appln. No. 10-2009-0051131, 6 pages. cited by applicant .
U.S. Office Action dated Aug. 25, 2015 issued in counterpart U.S.
Appl. No. 12/797,271, 12 pages. cited by applicant .
U.S. Final Office Action dated Nov. 4, 2015 issued in counterpart
U.S. Appl. No. 12/797,271, 13 pages. cited by applicant .
U.S. Office Action dated Nov. 4, 2015 issued in counterpart U.S.
Appl. No. 12/797,271, 13 pages. cited by applicant .
Huawei, "Discussion on Inbound Mobility from 3G Marco Cell to HNB",
R3-090802, 3GPP TSG-RAN WG3 Meeting#63bis, Mar. 23-26, 2008. cited
by applicant .
Huawei, "Discussion of Inbound Handover", R3-090932, 3GPP TSG-RAN
WG3#63bis, Mar. 23-26, 2009. cited by applicant .
Korean Office Action dated Apr. 10, 2015 issued in counterpart
application No. 10-2009-0051131. cited by applicant .
Alcatel-Lucent, Vodafone, "Congested H(e)NB Hybrid Access Mode
Cell", R3-091053, 3GPP TSG-RAN WG3 Meeting #64, May 4-8, 2009, 4
pages. cited by applicant .
ZTE, "Modification of Access Mode of CSG Cell", R3-091207, 3GPP TSG
RAN WG3 Meeting #64, May 4-8, 2009, 2 pages. cited by applicant
.
ETRI, "Access Mode Change of CSG Cell During Operation", R3-091800,
3GPP TSG-RAN WG3 Meeting #65, Aug. 24-28, 2009, 2 pages. cited by
applicant .
European Search Report dated Jun. 22, 2016 issued in counterpart
Appln. No. 10786343.3-1854, 7 pages. cited by applicant.
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Primary Examiner: Wu; Jianye
Attorney, Agent or Firm: The Farrell Law Firm, P.C.
Parent Case Text
PRIORITY
The present application is a Continuation of U.S. Ser. No.
12/797,271, which was filed in the U.S. Patent and Trademark Office
on Jun. 9, 2010, and claims priority under 35 U.S.C. .sctn.119(a)
to Korean Patent Application Serial No. 10-2009-0051131, which was
filed in the Korean Intellectual Property Office on Jun. 9, 2009,
the entire disclosure of each of which is hereby incorporated by
reference.
Claims
What is claimed is:
1. A method for changing an access mode of a second node B (NB), by
a core network (CN), in a wireless communication system, the method
comprising: receiving, from a first NB, a request to change the
access mode of the second NB from a first mode into a second mode
or from the second mode into the first mode; determining, by the
CN, to change the access mode of the second NB; transmitting, to
the second NB, a request message requesting to change the access
mode of the second NB; and receiving, from the second NB, a
response message informing of an access mode control result,
wherein the first mode allows access only to users or terminals
having a registration in the second NB, and the second mode allows
access to users or terminals, regardless of the registration in the
second NB, wherein, if the access mode of the second NB is changed
from the first mode to the second mode, the second NB further
grants access to at least one user or terminal not registered in
the second NB, and wherein, if the access mode of the second NB is
changed from the second mode to the first mode, the second NB
controls at least one user or terminal not registered in the second
NB to handover to a neighbor NB.
2. A method for changing an access mode by a node B (NB) of a
wireless communication system, the method comprising: receiving,
from a core network or another NB, a request message requesting to
change the access mode of the NB from a first mode into a second
mode or from the second mode into the first mode, wherein the first
mode allows access only to users or terminals having a registration
in the NB, and the second mode allows access to users or terminals
regardless of the registration in the NB; determining to change the
access mode; transmitting, to the core network or the another NB, a
response message informing of an access mode control result; if the
access mode of the NB is changed from the first mode to the second
mode, further granting access to at least one user or terminal not
registered in the NB; and if the access mode of the NB is changed
from the second mode to the first mode, controlling at least one
user or terminal not registered in the NB to handover to a neighbor
NB.
3. The method of claim 2, further comprising: transmitting a
request to an owner of the NB; and receiving, from the owner of the
NB, a response representing whether to allow an access mode change
of the NB.
4. The method of claim 2, further comprising: transmitting a system
information modification message informing that system information
is modified according to a change of the access mode; and
transmitting a system information message including information on
the changed mode.
5. A method for changing an access mode by a node B (NB) in a
wireless communication system, the method comprising: determining
to change the access mode of the NB from a first mode into a second
mode or from the second mode into the first mode, wherein the first
mode allows access only to users or terminals having a registration
in the NB, and the second mode allows access to users or terminals
regardless of the registration in the NB; transmitting, to a core
network (CN), a request message requesting to change the access
mode of the NB; receiving, from the CN, a response message
informing of an access mode control result to change the access
mode; if the access mode of the NB is changed from the first mode
to the second mode, further granting access to at least one user or
terminal not registered in the NB; and if the access mode of the NB
is changed from the second mode to the first mode, controlling at
least one user or terminal not registered in the NB to handover to
a neighbor NB.
6. The method of claim 5, further comprising: transmitting a
request to an owner of the NB; and receiving, from the owner of the
NB, a response indicating whether to allow an access mode change of
the NB.
7. The method of claim 5, further comprising: transmitting a system
information modification message informing that system information
is modified according to a change of the access mode; and
transmitting a system information message including information on
the changed mode.
8. The method of claim 5, wherein determining to change the access
mode of the NB comprises: exchanging load information including
respective cell load information with a plurality of NBs;
determining whether coverage areas of the NB and the neighbor NB
overlap each other, whether a cell load of the neighbor NB is
greater than a reference level, and whether a cell load of the NB
is less than the reference level, based on the load information for
each cell, and an inter-NB coverage mapping table; and when
determining that the coverage areas of the NB and the neighbor NB
overlap each other, the cell load of the neighbor NB is greater
than the reference level, and the cell load of the NB is less than
the reference level, determining to change the access mode of the
NB.
9. A first node B (NB) of a wireless communication system that
changes an access mode of a second NB, the first NB comprising: a
controller for determining to change the access mode of the second
NB from a first mode into a second mode or from the second mode
into the first mode; a transmitter for transmitting, to the second
NB, a request message requesting to change the access mode of the
second NB; and a receiver for receiving, from the second NB, a
response message informing of an access mode control result,
wherein the first mode allows access only to users or terminals
having a registration in the second NB, and the second mode allows
access to users or terminals, regardless of the registration in the
second NB, wherein, if the access mode of the second NB is changed
from the first mode to the second mode, the second NB further
grants access to at least one user or terminal not registered in
the second NB, and wherein, if the access mode of the second NB is
changed from the second mode to the first mode, the second NB
controls at least one user or terminal not registered in the second
NB to handover to a neighbor NB.
10. The first NB of claim 9, wherein the receiver receives a
measurement report message from a terminal, and wherein the
controller determines to change the access mode of the second NB,
when it is determined that the terminal receives an interference of
more than a reference level from the second NB, based on the
measurement report message.
11. The first NB of claim 9, wherein the receiver receives load
information including respective cell load information from a
plurality of NBs, and wherein the controller determines to change
the access mode of the second NB, when it is determined that
coverage areas of the first NB and the second NB overlap each
other, a cell load of the first NB is greater than a reference
level, and a cell load of the second NB is less than the reference
level, based on the load information and an inter-NB coverage
mapping table.
12. A node B (NB) of a wireless communication system that changes
an access mode of the NB, the NB comprising: a receiver for
receiving, from a core network (CN) or another NB, a request
message requesting to change the access mode of the NB from a first
mode into a second mode or from the second mode into the first
mode, wherein the first mode allows access only to users or
terminals having a registration in the NB, and the second mode
allows access to users or terminals regardless of the registration
in the NB; a controller for determining whether to change the
access mode; and a transmitter for transmitting, to the CN or the
another NB, a response message informing of an access mode control
result to change the access mode, wherein the controller, if the
access mode of the NB is changed from the first mode to the second
mode, further grants access to at least one user or terminal not
registered in the NB, and wherein the controller, if the access
mode of the NB is changed from the second mode to the first mode,
controls at least one user or terminal not registered in the NB to
handover to a neighbor NB.
13. The NB of claim 12, wherein the transmitter transmits a request
to an owner of the NB, and wherein the receiver receives, from the
owner of the NB, a response indicating whether to allow an access
mode change of the NB.
14. The NB of claim 12, wherein, when the controller determines to
allow the access mode change of the NB, the transmitter transmits a
system information modification message informing that system
information is modified according to a change of the access mode,
and transmits a system information message including information on
the changed mode.
15. A node B (NB) of a wireless communication system that changes
an access mode of the NB, the NB comprising: a controller for
determining to change the access mode of the NB from a first mode
into a second mode or from the second mode into the first mode,
wherein the first mode allows access only to users or terminals
having a registration in the NB, and the second mode allows access
to users or terminals regardless of the registration in the NB; a
transmitter for transmitting, to a core network (CN), a request
message requesting to change the access mode of the NB; and a
receiver for receiving, from the CN, a response message informing
of an access mode control result to change the access mode, wherein
the controller, if the access mode of the NB is changed from the
first mode to the second mode, further grants access to at least
one user or terminal not registered in the NB, and wherein the
controller, if the access mode of the NB is changed from the second
mode to the first mode, controls at least one user or terminal not
registered in the NB to handover to a neighbor NB.
16. The NB of claim 15, wherein the transmitter transmits a request
message to an owner of the NB, and wherein the receiver receives,
from the owner of the NB, a response message representing whether
to allow the access mode change of the NB.
17. The NB of claim 15, wherein the transmitter transmits a system
information modification message informing that system information
is modified according to a change of the access mode, and transmits
a system information message including information on the changed
mode.
18. The NB of claim 15, wherein the receiver receives load
information including respective cell load information from a
plurality of NBs, and wherein the controller determines to change
the access mode of the NB, when it is determined that coverage
areas of the NB and a neighbor NB overlap each other, a cell load
of the neighbor NB is greater than a reference level, and a cell
load of the NB is less than a reference level, based on the load
information for each cell and an inter-NB coverage mapping
table.
19. A method for changing an access mode of a second node B (NB),
by a first NB, of a wireless communication system, the method
comprising: determining to change the access mode of the second NB
from a first mode into a second mode or from the second mode into
the first mode; transmitting, to a core network (CN), a request
message requesting to change the access mode of the second NB; and
receiving, from the CN, a response message informing of an access
mode control result to change the access mode, wherein the first
mode allows access only to users or terminals having a registration
in the second NB, and the second mode allows access to users or
terminals, regardless of the registration in the second NB,
wherein, if the access mode of the second NB is changed from the
first mode to the second mode, the second NB further grants access
to at least one user or terminal not registered in the second NB,
and wherein, if the access mode of the second NB is changed from
the second mode to the first mode, the second NB controls at least
one user or terminal not registered in the second NB to handover to
a neighbor NB.
20. The method of claim 19, wherein determining to change the
access mode of the second NB comprises: receiving a measurement
report message from a terminal; determining whether the terminal
receives an interference of more than a reference level from the
second NB, based on the measurement report message; and when it is
determined that the terminal receives the interference of more than
the reference level from the second NB, determining to change of
the access mode of the second NB.
21. The method of claim 19, further comprising: exchanging load
information including respective cell load information with a
plurality of NBs; determining whether coverage areas of the first
NB and the second NB overlap each other, a cell load of the first
NB is greater than a reference level, and a cell load of the second
NB is less than the reference level, based on load information for
each cell and an inter-NB coverage mapping table; and when the
coverage areas of the first NB and the second NB overlap each
other, the cell load of the first NB is greater than the reference
level, and the cell load of the second NB is less than the
reference level, determining to change the access mode of the
second NB.
22. A method for changing an access mode of a second node B (NB),
by a core network (CN), of a wireless communication system, the
method comprising: determining to change the access mode of the
second NB from a first mode into a second mode or from the second
mode into the first mode; transmitting, to the second NB, a request
message requesting to change the access mode of the second NB; and
receiving, from the second NB, a response message informing of an
access mode control result to change the access mode, wherein the
first mode allows access only to users or terminals having a
registration in the second NB, and the second mode allows access to
users or terminals, regardless of the registration in the second
NB, wherein, if the access mode of the second NB is changed from
the first mode to the second mode, the second NB further grants
access to at least one user or terminal not registered in the
second NB, and wherein, if the access mode of the second NB is
changed from the second mode to the first mode, the second NB
controls at least one user or terminal not registered in the second
NB to handover to a neighbor NB.
23. The method of claim 22, wherein determining to change the
access mode of the second NB comprises: receiving load information
including respective cell load information from a plurality of NBs;
determining whether a first NB having a coverage that overlaps a
coverage area of the second NB and having a cell load that is
greater than a reference level exists, and a cell load of the
second NB is less than the reference level, based on load
information for each cell and an inter-NB coverage mapping table;
and when it is determined that the first NB having the coverage
that overlaps the coverage area of the second NB and having the
cell load that is greater than the reference level exists, and that
the cell load of the second NB is less than the reference level,
determining to change the access mode of the second NB.
24. A first node B (NB) of a wireless communication system, the
first NB comprising: a controller for determining to change an
access mode of a second NB from a first mode into a second mode or
from the second mode into the first mode; a transmitter for
transmitting, to core network (CN), a request message requesting to
change the access mode of the second NB; and a receiver for
receiving, from the CN, a response message informing of an access
mode control result to change the access mode, wherein the first
mode allows access only to users or terminals having a registration
in the second NB, and the second mode allows access to users or
terminals, regardless of the registration in the second NB,
wherein, if the access mode of the second NB is changed from the
first mode to the second mode, the second NB further grants access
to at least one user or terminal not registered in the second NB,
and wherein, if the access mode of the second NB is changed from
the second mode to the first mode, the second NB controls at least
one user or terminal not registered in the second NB to handover to
a neighbor NB.
25. The first NB of claim 24, wherein the receiver receives a
measurement report message from a terminal, and wherein the
controller determines to change the access mode of the second NB,
when it is determined that the terminal receives an interference of
more than a reference level from the second NB, based on the
measurement report message.
26. The first NB of claim 24, wherein the receiver receives load
information including respective cell load information from a
plurality of NBs, and wherein the controller determines to change
the access mode of the second NB, when it is determined that the
coverage areas of the first NB and the second NB overlap each
other, a cell load of the first NB is greater than a reference
level, and a cell load of the second NB is less than the reference
level, based on the load information for each cell and an inter-NB
coverage mapping table.
27. A method for changing an access mode of a second node B (NB),
by a first node NB, of a wireless communication system, the method
comprising: determining to change the access mode of the second NB
from a first mode into a second mode or from the second mode into
the first mode; transmitting, to the second NB, a request message
requesting to change the access mode of the second NB; and
receiving, from the second NB, a response message informing of an
access mode control result to change the access mode, wherein the
first mode allows access only to users or terminals having a
registration in the second NB, and the second mode allows access to
users or terminals, regardless of the registration in the second
NB, wherein, if the access mode of the second NB is changed from
the first mode to the second mode, the second NB further grants
access to at least one user or terminal not registered in the
second NB, and wherein, if the access mode of the second NB is
changed from the second mode to the first mode, the second NB
controls at least one user or terminal not registered in the second
NB to handover to a neighbor NB.
28. The method of claim 27, wherein determining to change the
access mode of the second NB comprises: receiving a measurement
report message from a terminal; determining whether the terminal
receives an interference of more than a reference level from the
second NB, based on the measurement report message; and when
determining that the terminal receives the interference of more
than the reference level from the second NB, determining to change
of the access mode of the second NB.
29. The method of claim 27, wherein determining to change the
access mode of the second NB comprises: exchanging load information
including respective cell load information with a plurality of NBs;
determining whether coverage areas of the first NB and the second
NB overlap each other, a cell load of the first NB is greater than
a reference level, and a cell load of the second NB is less than
the reference level, based on load information for each cell and an
inter-NB coverage mapping table; and when the coverage areas of the
first NB and the second NB overlap each other, the cell load of the
first NB is greater than the reference level, and the cell load of
the second NB is less than the reference level, determining to
change the access mode of the second NB.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an apparatus and a
method for managing an access mode of a Node B (NB) in a wireless
communication system. More particularly, the present invention
relates to an apparatus and a method for determining and changing
an access mode of an NB, depending on different factors in a
wireless communication system.
2. Description of the Related Art
In a conventional cellular communication system, an NB, which is
connected to a mobile communication core network, provides
communication services to User Equipments (UEs) that located within
a cell area of the NB.
When an amount of communication in a cell area of an NB is expected
to increase temporarily, for example, during a large gathering such
as a party or concert, a load of the cell is also expected to
increase temporarily, which may affect the quality of the
communication services provided by the NB. When this occurs, the
load of the cell may be distributed by temporarily adding a mobile
NB, e.g., an NB mounted on a vehicle, to the area where the amount
of communication is expected to be large.
Additionally, in a conventional cellular communication system, a
channel state often deteriorates due to a geographical condition
inside a cell, an increased distance between a UE and an NB, or
movement of a UE. For example, a shadowing area may be formed
inside a building, such as an office or a house, which is located
inside a coverage area of an NB. If a UE is located in the
shadowing area, an NB may not be able perform sufficient
communication because a channel state associated with the UE is
poor.
In order to improve communication in areas with poor channel
conditions, a femto-cell service may be utilized. A femto cell is a
small cell area formed by a compact NB that is commonly installed
inside an office or a house and that accesses a mobile
communication core network via a broadband network. The compact NB
is a low power NB, which is often installed by a user, not the
service provider and the compact NB may also be referred to as a
micro NB, a self configurable NB, an indoor NB, a home NB, or a
femto NB. In the following description, the compact NB is referred
to as a femto NB.
There are three access modes of a femto NB that are currently under
discussion in the current 3.sup.rd Generation Partnership Project
Long Term Evolution (3GPP LTE), which are defined as follows.
1. Open Access Mode: a mode that grants access to all users that
are not registered in an NB.
2. Closed Access Mode: a mode that grants access only to users that
are registered in an NB.
3. Hybrid Access Mode: a mode that that grants access to a user
that is registered in an NB, and also grants an access to users
that are not registered in the NB.
The above-defined various access modes of the femto NB may also be
applied to a mobile NB and a general macro NB.
Currently, when an NB is installed, e.g., a femto NB, a mobile NB,
or a general macro NB, an NB access mode is permanently set.
Accordingly, in an environment where neighbor NBs use the same
frequency, when a UE that receives a service from an NB that
utilizes an open access mode enters a coverage of an NB that
utilizes a closed access mode, a serious interference factor is
generated between the neighbor NBs that use the different access
modes, which deteriorates communication quality.
SUMMARY OF THE INVENTION
The present invention is designed to address at least the
above-mentioned problems and/or disadvantages occurring in the
prior art and to provide at least the advantages described below.
Accordingly, an aspect of the present invention is to provide an
apparatus and a method for managing an access mode of an NB in a
wireless communication system.
Another aspect of the present invention is to provide an apparatus
and a method for solving an interference problem that occurs
between neighbor NBs using different access modes, but the same
frequency, and providing a load balancing effect in a specific area
or when an event occurs by determining and changing an access mode
of an NB depending on different factors in a wireless communication
system.
In accordance with an aspect of the present invention, a method is
provided for changing an access mode of a second node B (NB), by a
core network (CN), in a wireless communication system. The method
includes receiving, from a first NB, a request to change the access
mode of the second NB from a first mode into a second mode;
determining, by the CN, to change the access mode of the second NB
into the second mode; transmitting, to the second NB, a request
message requesting to change the access mode of the second NB; and
receiving, from the second NB, a response message informing of an
access mode control result. If the first mode allows access only to
users or terminals having a registration in the second NB, and the
second mode allows access to users or terminals, regardless of the
registration in the second NB, the second NB further grants access
to at least one user or terminal not registered in the second NB,
after changing the access mode, and if the first mode allows access
to the users or the terminals, regardless of the registration in
the second NB, and the second mode allows access only to the users
or the terminals having the registration in the second NB, the
second NB controls at least one user or terminal not registered in
the second NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a
method is provided for changing an access mode by a node B (NB) of
a wireless communication system. The method includes receiving,
from a core network or another NB, a request message requesting to
change the access mode of the NB from a first mode into a second
mode; determining to change the access mode; transmitting, to the
core network or the another NB, a response message informing of an
access mode control result; if the first mode allows access only to
users or terminals having a registration in the NB, and the second
mode allows access to users or terminals, regardless of the
registration in the NB, further granting access to at least one
user or terminal not registered in the NB, after changing the
access mode; and if the first mode allows access to the users or
the terminals, regardless of the registration in the NB, and the
second mode allows access only to the users or the terminals having
the registration in the NB, controlling at least one user or
terminal not registered in the NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a
method is provided for changing an access mode by a node B (NB) in
a wireless communication system. The method includes determining to
change the access mode of the NB from a first mode into a second
mode; transmitting, to a core network (CN), a request message
requesting to change the access mode of the NB; receiving, from the
CN, a response message informing of an access mode control result
to change the access mode; if the first mode allows access only to
users or terminals having a registration in the NB, and the second
mode allows access to users or terminals, regardless of the
registration in the NB, further granting access to at least one
user or terminal not registered in the NB, after changing the
access mode; and if the first mode allows access to the users or
the terminals, regardless of the registration in the NB, and the
second mode allows access only to the users or the terminals having
the registration in the NB, controlling at least one user or
terminal not registered in the NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a first
node B (NB) of a wireless communication system is provided, which
changes an access mode of a second NB. The first NB includes a
controller for determining to change the access mode of the second
NB from a first mode into a second mode; a transmitter for
transmitting, to the second NB, a request message requesting to
change the access mode of the second NB; and a receiver for
receiving, from the second NB, a response message informing of an
access mode control result. If the first mode allows access only to
users or terminals having a registration in the second NB, and the
second mode allows access to users or terminals, regardless of the
registration in the second NB, the second NB further grants access
to at least one user or terminal not registered in the second NB,
after changing the access mode, and if the first mode allows access
to the users or the terminals, regardless of the registration in
the second NB, and the second mode allows access only to the users
or the terminals having the registration in the second NB, the
second NB controls at least one user or terminal not registered in
the second NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a node
B (NB) of a wireless communication system is provided, which
changes an access mode of the NB. The NB includes a controller for
determining to change the access mode of the NB from a first mode
into a second mode; a transmitter for transmitting, to a core
network (CN), a request message requesting to change the access
mode of the NB; and a receiver for receiving, from the CN, a
response message informing of an access mode control result to
change the access mode. If the first mode allows access only to
users or terminals having a registration in the NB, and the second
mode allows access to users or terminals, regardless of the
registration in the NB, further grants access to at least one user
or terminal not registered in the NB, after changing the access
mode, and the controller, if the first mode allows access to the
users or the terminals, regardless of the registration in the NB,
and the second mode allows access only to the users or the
terminals having the registration in the NB, controls at least one
user or terminal not registered in the NB to handover to a neighbor
NB.
In accordance with another aspect of the present invention, a node
B (NB) of a wireless communication system is provided, which
changes an access mode of the NB. The NB includes a receiver for
receiving, from a core network (CN) or another NB, a request
message requesting to change the access mode of the NB from a first
mode into a second mode; a controller for determining whether to
change the access mode; and a transmitter for transmitting, to the
CN or the another NB, a response message informing of an access
mode control result to change the access mode. The controller, if
the first mode allows access only to users or terminals having a
registration in the NB, and the second mode allows access to users
or terminals, regardless of the registration in the NB, further
grants access to at least one user or terminal not registered in
the NB, after changing the access mode, and the controller, if the
first mode allows access to the users or the terminals, regardless
of the registration in the NB, and the second mode allows access
only to the users or the terminals having the registration in the
NB, controls at least one user or terminal not registered in the NB
to handover to a neighbor NB.
In accordance with another aspect of the present invention, a
method is provided for changing an access mode of a second node B
(NB), by a first NB, of a wireless communication system. The method
includes determining to change the access mode of the second NB
from a first mode into a second mode; transmitting, to a core
network (CN), a request message requesting to change the access
mode of the second NB; and receiving, from the CN, a response
message informing of an access mode control result to change the
access mode. If the first mode allows access only to users or
terminals having a registration in the second NB, and the second
mode allows access to users or terminals, regardless of the
registration in the second NB, the second NB further grants access
to at least one user or terminal not registered in the second NB,
after changing the access mode, and if the first mode allows access
to the users or the terminals, regardless of the registration in
the second NB, and the second mode allows access only to the users
or the terminals having the registration in the second NB, the
second NB controls at least one user or terminal not registered in
the second NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a
method is provided for changing an access mode of a second node B
(NB), by a core network (CN), of a wireless communication system.
The method includes determining to change the access mode of the
second NB from a first mode into a second mode; transmitting, to
the second NB, a request message requesting to change the access
mode of the second NB; and receiving, from the second NB, a
response message informing of an access mode control result to
change the access mode. If the first mode allows access only to
users or terminals having a registration in the second NB, and the
second mode allows access to users or terminals, regardless of the
registration in the second NB, the second NB further grants access
to at least one user or terminal not registered in the second NB,
after changing the access mode, and if the first mode allows access
to the users or the terminals, regardless of the registration in
the second NB, and the second mode allows access only to the users
or the terminals having the registration in the second NB, the
second NB controls at least one user or terminal not registered in
the second NB to handover to a neighbor NB.
In accordance with another aspect of the present invention, a first
node B (NB) of a wireless communication system is provided. The
first NB includes a controller for determining to change an access
mode of a second NB from a first mode into a second mode; a
transmitter for transmitting, to core network (CN), a request
message requesting to change the access mode of the second NB; and
a receiver for receiving, from the CN, a response message informing
of an access mode control result to change the access mode. If the
first mode allows access only to users or terminals having a
registration in the second NB, and the second mode allows access to
users or terminals, regardless of the registration in the second
NB, the second NB further grants access to at least one user or
terminal not registered in the second NB, after changing the access
mode, and if the first mode allows access to the users or the
terminals, regardless of the registration in the second NB, and the
second mode allows access only to the users or the terminals having
the registration in the second NB, the second NB controls at least
one user or terminal not registered in the second NB to handover to
a neighbor NB.
In accordance with another aspect of the present invention, a
method is provided for changing an access mode of a second node B
(NB), by a first node NB, of a wireless communication system. The
method includes determining to change the access mode of the second
NB from a first mode into a second mode; transmitting, to the
second NB, a request message requesting to change the access mode
of the second NB; and receiving, from the second NB, a response
message informing of an access mode control result to change the
access mode. If the first mode allows access only to users or
terminals having a registration in the second NB, and the second
mode allows access to users or terminals, regardless of the
registration in the second NB, the second NB further grants access
to at least one user or terminal not registered in the second NB,
after changing the access mode, and if the first mode allows access
to the users or the terminals, regardless of the registration in
the second NB, and the second mode allows access only to the users
or the terminals having the registration in the second NB, the
second NB controls at least one user or terminal not registered in
the second NB to handover to a neighbor NB.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects, features, and advantages of certain
embodiments of the present invention will be more apparent from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
FIG. 1 illustrates an example of an interference factor of an
access mode decision and change factors of an NB in a wireless
communication system according to an embodiment of the present
invention;
FIG. 2 is a signal flow illustrating a method for changing an NB
access mode by an interference factor at an NB of a wireless
communication system according to an embodiment of the present
invention;
FIG. 3 is a signal flow illustrating a method for changing an NB
access mode by an interference factor at an NB of a wireless
communication system according to an embodiment of the present
invention;
FIG. 4 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention;
FIG. 5 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention;
FIG. 6 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention;
FIG. 7 is a signal flow illustrating a management method for
determining, at an NB, an access mode, and reporting the access
mode to a Core Network (CN) in a wireless communication system
according to an embodiment of the present invention;
FIG. 8 is a signal flow illustrating a management method for
determining, at a CN, an access mode of an NB and reporting the
access mode to the NB in a wireless communication system according
to an embodiment of the present invention;
FIG. 9 is a signal flow illustrating a management method for
requesting, by a neighbor NB, an NB to change an access mode for
the purpose of reducing an inter-cell interference in a wireless
communication system according to an embodiment of the present
invention;
FIG. 10 is a signal flow illustrating a management method for
requesting, by a neighbor NB, an NB to change an access mode for
the purpose of reducing an inter-cell interference in a wireless
communication system according to an embodiment of the present
invention;
FIG. 11 is a signal flow illustrating an operating method for cases
1 and 2 for changing an access mode of an NB from a hybrid access
mode or an open access mode to a closed access mode in a wireless
communication system according to an embodiment of the present
invention;
FIG. 12 is a signal flow illustrating an operating method for case
3 for changing an access mode of an NB from a closed access mode to
a hybrid access mode in a wireless communication system according
to an embodiment of the present invention;
FIG. 13 is a signal flow illustrating an operating method for case
3 for changing an access mode of an NB from a closed access mode to
a hybrid access mode in a wireless communication system according
to an embodiment of the present invention;
FIG. 14 is a signal flow illustrating an operating method for case
3 for changing an access mode of an NB from a closed access mode to
a hybrid access mode in a wireless communication system according
to an embodiment of the present invention;
FIG. 15 is a signal flow illustrating an operating method for case
4 for changing an access mode of an NB from an open access mode to
a hybrid access mode in a wireless communication system according
to an embodiment of the present invention;
FIG. 16 is a flowchart illustrating an operating method of an NB,
for changing an access mode of a neighbor NB according to a request
from the NB in a wireless communication system according to an
embodiment of the present invention;
FIG. 17 is a flowchart illustrating an operating method of a
neighbor NB, for changing an access mode of the neighbor NB
according to a request from an NB in a wireless communication
system according to an embodiment of the present invention;
FIG. 18 is a flowchart illustrating an operating method of an NB,
for changing an access mode of the NB according to a request from
the NB in a wireless communication system according to an
embodiment of the present invention; and
FIG. 19 is a block diagram illustrating an NB according to an
embodiment of the present invention.
Throughout the drawings, like reference numerals will be understood
to refer to like parts, components and structures.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Various embodiments of the present invention are described herein
below. The matters defined in the description such as detailed
constructions and elements are provided to assist in a
comprehensive understanding of the embodiments of the invention.
Accordingly, those of ordinary skill in the art will recognize that
various changes and modifications of the embodiments described
herein can be made without departing from the scope and spirit of
the invention. Also, descriptions of well-known functions and
constructions are omitted for clarity and conciseness.
In the following description, a wireless communication system
denotes, for example, a communication system that uses an
Orthogonal Frequency Division Multiplexing (OFDM) scheme or an
Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
Although certain embodiments of the present invention are described
using a broadband wireless access communication system as an
example, the present invention is also applicable to different
wireless communication systems.
In the following description, an NB may be a macro NB or a femto
NB. Further, an NB that operates in an open access mode is referred
to as an open NB, an NB that operates in a closed access mode is
referred to as a closed NB, and an NB that operates in a hybrid
access mode is referred to as a hybrid NB. In addition, a UE that
is registered in an NB that operates in the closed access mode and
that is granted access is referred to as a closed user or a Closed
Subscriber Group (CSG) UE, and the other UEs are referred to as
open users or non-CSG UEs. Additionally, a coverage area of an NB
that operates in an open access mode is referred to as an open
cell, a coverage area of an NB that operates in a closed access
mode is referred to as a closed cell, and a coverage area of an NB
that operates in a hybrid access mode is referred to as a hybrid
cell. Here, the closed cell may also be referred to as a CSG cell,
and the open cell and the hybrid cell may also be referred to as a
non-CSG cell.
In the following description, a Core Network (CN) denotes a Mobile
Management Entity (MME), a Serving General packet radio service
(GPRS) Support Node (SGSN), a Mobile Switching Center (MSC), an
Access Control Router (ACR), Operations & Maintenance (OAM), a
Gate-Way (GW), etc.
The determination to change a current access mode and selection of
a new access mode of the NB may be performed right after a new NB
is installed or power is turned on, and an access mode change
during an operation may be performed due to the following other
factors. Also, an access mode change may be performed right after a
new NB is installed or power is turned on due to the following
other factors.
1. Interference factor: When neighbor NBs use the same frequency
and a non-CSG UE receives a service from an NB that utilizes an
open access mode, i.e., an open NB, or an NB that utilizes a hybrid
access mode, i.e., a hybrid NB, enters a coverage of an NB hat
utilizes a closed access mode, i.e., a closed NB, a serious
interference factor is generated between the neighbor NBs that use
the different access modes, seriously deteriorating communication
quality. In this case, to reduce the interference generated between
the neighbor NBs, the closed NB may provide a service by
temporarily changing its access mode and granting access to a
non-CSG UE.
2. Load distribution necessity factor: When an amount of
communication in an area will greatly increase, e.g., during a
concert or sporting event, and a load of a cell of an NB will
increase, load distribution may be required. In this case, with
respect to a closed NB, when the access mode is temporarily changed
to an open access mode with permission of a person who has
installed the closed NB, the load of the cell may be distributed
without a separate procedure.
When a CSG UE registered in a femto NB is located inside a coverage
of the femto NB in operation in the open access mode, the femto NB
may provide a service by temporarily changing its access mode and
allowing access by the CSG UE.
Due to the change of an NB access mode by the above-described
factors, system information such as a Physical Cell Identifier
(PCI) for identifying cells, a CSG indicator representing whether a
cell is a CSG cell, a CSG IDentifier (ID) for identifying CSG
cells, etc., is changed, and an NB notifies a UE that receives a
service from the NB that the system information has changed and
informs the UE of the changed system information.
FIG. 1 illustrates an example of an interference factor of an NB in
a wireless communication system according to an embodiment of the
present invention.
Referring to FIG. 1, when neighbor NBs (open or hybrid NB 110 and
closed NB 120) use the same frequency band and a non-CSG UE 100
receives a service from an open NB or a hybrid NB 110 enters a
coverage of a closed NB 120, interference is generated between the
neighbor NBs that use the different access modes.
The open NB or hybrid NB 110, which is a serving NB of the non-CSG
UE 100 may recognize that a CSG cell exists near the non-CSG UE 100
through a measurement report message of the non-CSG UE 100. That
is, the serving NB 110 may recognize that a communication
environment of the non-CSG UE 100 is degrading and that the CSG
cell is transmitting a strong signal exists through the measurement
report message of the non-CSG UE 100. At this point, the
communication between the non-CSG UE 100 and the serving NB 110
becomes an interference factor acting on the CSG cell, and a strong
signal that the non-CSG UE 100 receives from the CSG cell
deteriorates communication quality of the non-CSG UE 100.
When the non-CSG UE 100 receives a strong signal in the CSG cell,
and the non-CSG UE 100 causes interference while moving with low
speed and remaining in the area, the serving NB 110 requests the
closed NB 120 to change an access mode and allows the closed NB 120
to accept the non-CSG UE 100, thereby solving the interference
problem.
FIG. 2 is a signal flow illustrating a method for changing an NB
access mode by an interference factor at an NB of a wireless
communication system according to an embodiment of the present
invention.
Referring to FIG. 2, it is assumed that a CSG UE 210 is connected
to a closed NB 230 and receives a service in step 201, and a
non-CSG UE 200 is connected to a open or hybrid NB 220 and receives
a service in step 203. Under these assumptions, the non-CSG UE 200
enters a coverage of the closed NB 230, the CSG UE 210 and the
non-CSG UE 200 receive closed access system info.-message
transmitted by the closed NB 230 in step 205 and step 207,
respectively. The non-CSG UE 200 may detect a CSG cell that
transmits a strong signal, and recognize a PCI of the detected CSG
cell through the system info.-message received from the detected
CSG cell. Therefore, the non-CSG UE 200 informs its serving NB,
i.e., the open or hybrid NB 220, of the PCI of the CSG cell that
transmits a strong signal by transmitting a measurement report
message to the serving NB 220 in step 209.
The serving NB 220 that has received the measurement report message
from the non-CSG UE 200 determines whether the non-CSG UE 200
receives interference from the neighbor CSG cell, which is greater
than a reference level, based on the PCI included in the
measurement report message. If the non-CSG UE 200 receives
interference that is greater than the reference level from the
neighbor CSG cell, the non-CSG UE 200 may reduce the interference
of the UE and improve communication quality by handing over the UE
to the neighbor CSG cell, such that it receives a service from the
neighbor CSG cell, i.e., the closed NB 230, rather than receiving a
service from the serving NB 220. Therefore, when determining that
the non-CSG UE 200 receives interference greater than the reference
level from the neighbor CSG cell, in step 211, the serving NB 220
determines to perform a handover of the non-CSG UE 200, and
determines an access mode change request to the closed NB 230,
i.e., target NB, so that the target NB 230 may allow access of the
non-CSG UE 200. Here, to prevent the handover decision and access
mode change request decision from frequently occurring, the
handover decision and the access mode change request decision may
be performed when the non-CSG UE 200 receives interference greater
than the reference level from the neighbor CSG cell and the
velocity of the non-CSG UE 200 is less than a reference level.
To handover the non-CSG UE 200 and request an access mode change by
the closed NB 230, the serving NB 220 requests additional CSG cell
information, such as an Evolved Universal Mobile Telecommunications
System (UMTS) Terrestrial Radio Access Network (E-UTRAN) Cell
Global Identifier (ECGI), for more accurate cell identification
than just the PCI, by transmitting an additional measurement
control message to the non-CSG UE 200, in step 213. The non-CSG UE
200 collects the CSG cell information and transmits the collected
information to the serving NB 220.
In step 215, the serving NB 220 transmits a Handover (HO) &
access mode change request message to a CN 240 using the CSG cell
information transmitted by the non-CSG UE 200. Here, the HO &
access mode change request message requests the non-CSG UE 200 to
perform a handover to the target NB 230, and requests the target NB
230 to change its access mode so that the non-CSG UE 200 may access
the target NB 230. Though the handover request and the access mode
change request are performed together in FIG. 2, they also may be
performed separately, e.g., using two separate request
messages.
The CN 240 controls an access mode of the target NB 230 in step
217. Specifically, when the CN 240 has an allowance authority
regarding the handover and the access mode change, the CN 240 may
determine whether to allow the handover and the access mode change
through a separate handover & access mode change algorithm.
However, when the CN 240 does not have the allowance authority
regarding the handover and the access mode change, the CN 240 may
determine allowance with respect to the handover and the access
mode change unconditionally. When the CN 240 determines allowance
regarding the handover of the non-CSG UE 200 and the access mode
change of the target NB 230, the CN 240 transfers the HO &
access mode change request message to the target NB 230 in step
219.
The target NB 230 controls its access mode in step 221. That is,
the target NB 230 determines whether to accept the handover of the
non-CSG UE 200, and determines whether to allow an access mode
change so that the non-CSG UE 200 may access the target NB 230.
When the target NB 230 is a femto NB, the target NB 230 may
additionally receive an allowance from an owner of the femto NB to
change the access mode.
The target NB 230 transmits an HO & access mode change response
message including an access mode control result to the CN 240 in
step 225, and the CN 240 transfers the HO & access mode change
response message including a final access mode control result to
the serving NB 220 in step 227. When allowance is determined with
respect to the handover of the non-CSG UE 200 and the access mode
change of the target NB 230 as the final access mode control
result, the serving NB 220 orders the non-CSG UE 200 to perform the
handover to the target NB 230 by transmitting a handover command
message to the non-CSG UE 200 in step 229.
When the target NB 230 determines an allowance with respect to the
handover of the non-CSG UE 200 and the access mode change of itself
through the access mode control, the target NB 230 informs the CSG
UE 210 that the access mode has changed, and accordingly the system
information has changed, by transmitting a system information
modification message to the CSG UE 210 in step 223. For example,
the target NB 230 may change its access mode from a closed access
mode to a hybrid access mode so that not only the CSG UE 210, but
also the non-CSG UE 200, may access the target NB 230. In this
case, the target NB 230 may transmit a hybrid access system
info.-message including system information of the changed access
mode to the CSG UE 210 and the non-CSG UE 200 in steps 231 and step
233.
In step 235, the non-CSG UE 200 accesses the target NB 230 and
receives a service from the target NB 230 by performing a general
handover procedure.
Though both the CN 240 and the target NB 230 perform the access
mode control in FIG. 2, alternatively, only one of them may perform
the access mode control.
In FIG. 2, the transfer of the HO & access mode change request
message has been described using an example in which the serving NB
220 transfers the HO & access mode change request message to
the target NB 230 via the CN 240. However, when direct
communication, such as an X2 interface between NBs is possible, the
serving NB 220 may directly transfer the HO & access mode
change request message to the target NB 230, which will be
described in more detail with reference to FIG. 3.
FIG. 3 is a signal flow illustrating a method for changing an NB
access mode by an interference factor at an NB of a wireless
communication system according to an embodiment of the present
invention.
FIG. 3 is basically the same as FIG. 2, i.e., steps 201 to 213 of
FIG. 2 are the same as steps 301 to 313 of FIG. 3, and thus, a
repetitive description will be avoided.
Referring to FIG. 3, in step 315, a serving NB 320 transmits an HO
& access mode change request message to a target NB 330 using
CSG cell information transmitted by a non-CSG UE 300. Here, the HO
& access mode change request message requests the non-CSG UE
300 to perform a handover to the target NB 330, and requests the
target NB 330 to change its access mode so that the non-CSG UE 300
may access the target NB 330. Though the handover request and the
access mode change request are performed together in FIG. 3,
alternatively, they may be performed separately.
In step 317, the target NB 330 controls its access mode. That is,
the target NB 330 determines whether to accept a call of the
non-CSG UE 300, and determines whether to allow an access mode
change so that the non-CSG UE 300 may access the target NB 330. If
the target NB 330 is a femto NB, the target NB may additionally
receiving an allowance from an owner of the femto NB to change the
access mode.
When the target NB 330 determines an allowance with respect to the
handover of the non-CSG UE 300 and the access mode change of the
target NB 330, the target NB 330 transfers the HO & access mode
change request message to a CN 340 in step 319.
In step 321, the CN 340 controls the access mode of the target NB
330. Specifically, when the CN 340 has an allowance authority
regarding the handover and the access mode change, the CN 340
determines whether to allow the handover and the access mode change
through a separate handover & access mode change algorithm.
However, when the CN 340 does not have the allowance authority
regarding the handover and the access mode change, the CN 340 may
determine allowance with respect to the handover and the access
mode change unconditionally.
The CN 340 transmits an HO & access mode change response
message including an access mode control result to the target NB
330 in step 323, and the target NB 330 transfers an HO & access
mode change response message including a final access mode control
result to the serving NB 320 in step 327. When allowance is
determined with respect to the handover of the non-CSG UE 300 and
the access mode change of the target NB 330 as the final access
mode control result, the serving NB 320 may order the non-CSG UE
300 to perform the handover to the target NB 330 by transmitting a
handover command message to the non-CSG UE 300 in step 329.
When the target NB 330 determines an allowance with respect to the
handover of the non-CSG UE 300 and its access mode change as the
final access mode control result, the target NB 330 informs the CSG
UE 310 that the access mode has changed, and accordingly that the
system information has changed, by transmitting a system
information modification message to the CSG UE 310 in step 325. For
example, the target NB 330 may change its access mode to a hybrid
access mode so that not only the CSG UE 310, but also the non-CSG
UE 300, may access the target NB 330. In this case, the target NB
330 may transmit a hybrid access system info.-message including
system information of the changed access mode to the CSG UE 310 and
the non-CSG UE 300 in step 331 and step 333, respectively.
The non-CSG UE 300 accesses the target NB 330 and receives a
service from the target NB 330 by performing a general handover
procedure in step 335.
Though both the CN 340 and the target NB 330 perform the access
mode control in FIG. 3, alternatively, only one of them may perform
the access mode control. That is, the target NB 330 that has
received an HO & access mode change request message from the
serving NB 320 may directly transmit an HO & access mode change
response message, including only an access mode control performance
result of the target NB, to the serving NB 320.
FIG. 4 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention.
Referring to FIG. 4, it is assumed that a CSG UE 410 is connected
to a closed NB 430 as a closed user to receive a service in step
401, and a non-CSG UE 400 is connected to an open or hybrid NB 420
as an open user to receive a service in step 405. In addition, it
is assumed that the closed NB 430, which is a neighbor NB to the
non-CSG UE 400, and open or hybrid NB, i.e., the serving NB, 420 of
the non-CSG UE 400 transmit load info.-messages including cell load
information to a CN 440 in step 403 and step 407, respectively.
Based on these assumptions, the non-CSG UE 400 enters a coverage of
the neighbor NB 430, the CSG UE 410 and the non-CSG UE 400 receive
closed access system info.-messages transmitted by the neighbor NB
430 of the closed access mode in steps 409 and 411,
respectively.
The CN 440 determines whether an NB whose cell load is greater than
a reference level and an NB whose cell load is less than the
reference level exist among NBs whose coverage areas overlap, based
on the load information for each cell and an inter-NB coverage
mapping table. If an NB whose cell load is greater than the
reference level and an NB whose cell load is less than the
reference level exist among the NBs with overlapping coverage
areas, the CN 440 may distribute a cell load by changing an access
mode of the NB whose cell load is less than the reference level so
that a UE that receives a service from an NB whose cell load is
greater than the reference level may perform a handover to the NB
whose cell load is less than the reference level.
Referring to FIG. 4, when an NB whose cell load is greater than the
reference level and an NB whose cell load is less than the
reference level exist among the NBs with overlapping coverage
areas, the CN 440 determines whether to request the NB whose cell
load is less than the reference level to change an access mode in
step 413. For example, when the coverage areas of the serving NB
420 and the neighbor NB 430 of the non-CSG UE 400 overlap each
other, and the cell load of the serving NB 420 is greater than the
reference level and the cell load of the neighbor NB 430 is less
than the reference level, the CN 440 determines to request the
neighbor NB 430 to change an access mode so that the non-CSG UE 400
may perform a handover to the neighbor NB 430 whose cell load is
less than the reference level and receive service from the neighbor
NB 430.
In step 415, the CN 440 transmits an access mode change request
message to the neighbor NB 430. Here, the access mode change
request message requests the neighbor NB 430 to change its access
mode so that the non-CSG UE 400 may access the neighbor NB 430.
In step 417, the neighbor NB 430 controls its access mode.
Specifically, the neighbor NB 430 determines whether to allow its
access mode to change so that the non-CSG UE 400 may access the
neighbor NB 430. When the neighbor NB 430 is a femto NB, the
neighbor NB may additionally receive an allowance from an owner of
the femto NB to change its access mode. That is, the neighbor NB
may transmit an access mode change request message to the owner 410
of the femto NB and receive an access mode change response message
from the owner 410 of the femto NB in step 419.
In step 421, the neighbor NB 430 transmits an access mode change
response message including an access mode control result to the CN
440. When determining an allowance with respect to its access mode,
the neighbor NB 430 informs the CSG UE 410 that the access mode has
changed, and accordingly, that the system information has changed,
by transmitting a system information modification message to the
CSG UE 410 in step 423. For example, the neighbor NB 430 may change
its access mode to a hybrid access mode so that not only the CSG UE
410, but also the non-CSG UE 400, may access the neighbor NB 430.
In this case, the neighbor NB 430 may transmit a hybrid access
system info.-message including system information of the changed
access mode to the CSG UE 410 and the non-CSG UE 400 in steps 425
and 427, respectively.
In step 429, the non-CSG UE 400 generates a measurement report
message based on the system info.-message received from the
neighbor NB 430, and transmits the same to the serving NB 420. The
serving NB 420 determines a handover of the non-CSG UE 400 based on
the measurement report message in step 431. When the serving NB
transmits a handover command message to the non-CSG UE 400
according to the handover decision of the non-CSG UE 400, the
non-CSG UE 400 is connected to the neighbor NB 430 and receives a
service from the neighbor NB 430 by performing a general handover
procedure in step 433.
In FIG. 4, the CN 440 requests an NB whose cell load is less than a
reference level to change an access mode to allow a UE inside a
coverage area of an NB whose cell load is greater than the
reference level to access the NB whose cell load is less than the
reference level and receive service from the NB whose cell load is
less than the reference level. Specifically, FIG. 4 illustrates the
changing an access mode of an NB based on a request by a CN.
However, it is also possible for an access mode of an NB to be
changed based on a request of a neighbor NB. That is, an NB whose
cell load is greater than a reference level may request an NB whose
cell load is less than the reference level to change an access
mode, which will be described in more detail with reference to FIG.
5.
As another example, an NB may spontaneously request to change its
access mode. That is, an NB whose cell load is less than a
reference level may request to change its own access mode, which
will be described in more detail with reference to FIG. 6.
FIG. 5 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention.
Referring to FIG. 5, it is assumed that a CSG UE 510 is connected
to a closed NB 530 as a closed user to receive a service in step
501, and a non-CSG UE 500 is connected to a open or hybrid NB 520
as an open user to receive a service in step 503. Under these
assumptions, the non-CSG UE 500 enters a coverage area of the
closed NB 530, which is a neighbor NB, and the CSG UE 510 and the
non-CSG UE 500 receive closed access system info.-messages
transmitted by the neighbor NB 530 in steps 505 and 507,
respectively.
In addition, NBs 520 and 530 exchange a load info.-message,
including cell load information, with each other in steps 509 and
511. The NBs 520 and 530 determine whether an NB whose cell load is
greater than a reference level and an NB whose cell load is less
than the reference level exist among NBs including the NBs 520 and
530, whose coverage areas overlaps those of the NBs 520 and 530,
based on the load information for each cell collected through the
load info.-message exchange and an inter-NB coverage mapping
table.
When an NB whose cell load is greater than the reference level and
an NB whose cell load is less than the reference level exist among
the NBs whose coverage areas overlap, the NBs 520 and 530 may
distribute the cell load by changing an access mode of the NB whose
cell load is less than the reference level so that a UE that
receives a service from the NB whose cell load is greater than the
reference level may perform a handover to the NB whose cell load is
less than the reference level. Therefore, when an NB whose cell
load is greater than the reference level and an NB whose cell load
is less than the reference level exist among the NBs whose coverage
areas overlap those of the NBs 520 and 530, the NB 520 or 530
determines whether the NB whose cell load is greater than the
reference level is itself, and when the NB is itself, the NB 520 or
530 determines to request the NB whose cell load is less than the
reference level to change an access mode in step 513.
For example, when the coverage of the serving NB 520 of the non-CSG
UE 500 overlaps the coverage of the neighbor NB 530, the cell load
of the serving NB 520 is greater than the reference level, and the
cell load of the neighbor NB 530 is less than the reference level,
the serving NB 520 determines whether to request the neighbor NB
530 to change an access mode so that the non-CSG UE 500 may perform
a handover to the neighbor NB 530 whose cell load is less than the
reference level to receive a service from the neighbor NB 530.
More specifically, the serving NB 520 transmits an access mode
change request message to the neighbor NB 530 in step 515. Here,
the access mode change request message requests the neighbor NB 530
to change its access mode so that the non-CSG UE 500 may access the
neighbor NB 530.
In step 517, the neighbor NB 530 controls its access mode.
Specifically, the neighbor NB 530 determines whether to allow its
access mode to change so that the non-CSG UE 500 may access the
neighbor NB 530.
When the neighbor NB 530 is a femto NB, the neighbor NB 530 may
additionally receive an allowance from an owner of the femto NB to
change the access mode. That is, the neighbor NB 530 may
additionally transmit an access mode change request message to the
owner 510 of the femto NB and receive an access mode change
response message from the owner 510 of the femto NB in step
519.
When the neighbor NB 530 determines to allow its access mode to
change, the neighbor NB 530 transfers the access mode change
request message to a CN 540 in step 521.
In step 523, the CN 540 controls an access mode of the neighbor NB
530. Specifically, when the CN 540 has an allowance authority
regarding the access mode change, the CN 540 may determine whether
to allow the access mode change through a separate access mode
change algorithm. However, when the CN 540 does not have the
allowance authority regarding the access mode change, the CN 540
may unconditionally determine allowance with respect to the access
mode change.
In step 525, the CN 540 transmits an access mode change response
message including an access mode control result to the neighbor NB
530, and in step 527, the neighbor NB 530 transfers an access mode
change response message including a final access mode control
result to the serving NB 520.
When determining an allowance with respect to its access mode
change as the final access mode control result, the neighbor NB 530
informs the CSG UE 510 that the access mode has changed, and
accordingly, that the system information has changed, by
transmitting a system information modification message to the CSG
UE 510 in step 529. For example, the neighbor NB 530 may change its
access mode to a hybrid access mode so that the CSG UE 510 and also
the non-CSG UE 500 may access the neighbor NB 530. In this case,
the neighbor NB 530 may transmit a hybrid access system
info.-message including system information of the changed access
mode to the CSG UE 510 and the non-CSG UE 500 in steps 531 and 533,
respectively.
In step 535, the non-CSG UE 500 generates a measurement report
message based on the system info.-message received from the
neighbor NB 530, and transmits the same to the serving NB 520. The
serving NB 520 determines a handover of the non-CSG UE 500 based on
the measurement report message in step 537. When the serving NB 520
transmits a handover command message to the non-CSG UE 500
according to a handover decision of the non-CSG UE 500, the non-CSG
UE 500 receives a service from the neighbor NB 530 by performing a
general handover procedure and accessing the neighbor NB 530 in
step 539.
FIG. 6 is a signal flow illustrating a method for changing an NB
access mode by a cell load distribution necessity factor at an NB
of a wireless communication system according to an embodiment of
the present invention.
Referring to FIG. 6, it is assumed that a CSG UE 610 is connected
to a closed NB 630 as a closed user to receive a service in step
601, and a non-CSG UE 600 is connected to an open or hybrid NB 620
as an open user to receive a service in step 603. Under these
assumptions, the non-CSG UE 600 enters a coverage of the closed NB
630, which is a neighbor NB, and the CSG UE 610 and the non-CSG UE
600 receive closed access system info.-message transmitted by the
neighbor NB 630 in steps 605 and 607, respectively.
In addition, the NBs 620 and 630 exchange load info.-message
including cell load information with each other. The NBs 620 and
630 determine whether an NB whose cell load is greater than a
reference level and an NB whose cell load is less than the
reference level exist among NBs including the NBs 620 and 630,
whose coverage areas overlap those of the NBs 620 and 630, based on
the load information for each cell collected through the load
info.-message exchange and an inter-NB coverage mapping table.
When an NB whose cell load is greater than the reference level and
an NB whose cell load is less than the reference level exist among
the NBs whose coverage areas overlap, the NBs 620 and 630 may
distribute the cell load by changing an access mode of the NB whose
cell load is less than the reference level so that a UE that
receives a service from the NB whose cell load is greater than the
reference level may perform a handover to the NB whose cell load is
less than the reference level.
Therefore, when an NB whose cell load is greater than the reference
level and an NB whose cell load is less than the reference level
exist among the NBs whose coverage areas overlap those of the NBs
620 and 630, the NB 620 or 630 determines whether the NB whose cell
load is less than the reference level is itself, and when the NB is
itself, the NB 620 or 630 determines whether to change its own
access mode in step 609.
For example, when the coverage area of the serving NB 620 of the
non-CSG UE 600 overlap the coverage area of the neighbor NB 630,
the cell load of the serving NB 620 is greater than the reference
level, and the cell load of the neighbor NB 630 is less than the
reference level, the neighbor NB 630 determines to change its
access mode so that the non-CSG UE 600 may perform a handover to
the neighbor NB 630 to receive service from the neighbor NB
630.
Additionally, when the neighbor NB 630 is a femto NB, the neighbor
NB may additionally receive an allowance from an owner of the femto
NB to change the access mode. That is, the neighbor NB may
additionally transmit an access mode change request message to the
owner 610 of the femto NB and receive an access mode change
response message from the owner 610 of the femto NB in step
611.
The neighbor NB 630 transmits an access mode change request message
to the CN 640 in step 613. Here, the access mode change request
message requests the neighbor NB 630 to change its access mode so
that the non-CSG UE 600 may access the neighbor NB 630.
In step 615, the CN 640 controls the access mode of the neighbor NB
630. Specifically, when the CN 640 has an allowance authority
regarding the access mode change, the CN 640 may determine whether
to allow the access mode change through a separate access mode
change algorithm. However, when the CN 640 does not have the
allowance authority regarding the access mode change, the CN 640
may unconditionally determine an allowance with respect to the
access mode change.
The CN 640 transmits an access mode change response message
including an access mode control result to the neighbor NB 630 in
step 617. When determining an allowance with respect to the access
mode change of the neighbor NB 630, the neighbor NB 630 informs the
CSG UE 610 that the access mode has changed, and accordingly, that
the system information has changed, by transmitting a system
information modification message to the CSG UE 610 in step 619.
For example, the neighbor NB 630 may change its own access mode to
a hybrid access mode so that the CSG UE 610 and the non-CSG UE 600
may access the neighbor NB 630. In this case, the neighbor NB 630
may transmit hybrid access system info.-messages including system
information of the changed access mode to the CSG UE 610 and the
non-CSG UE 600 in steps 621 and 623, respectively.
In step 625, the non-CSG UE 600 generates a measurement report
message based on the system info.-message received from the
neighbor NB 630, and transmits the same to the serving NB 620 of
the non-CSG UE 600. The serving NB 620 determines a handover of the
non-CSG UE 600 based on the measurement report message in step 627.
When the serving NB 620 transmits a handover command message to the
non-CSG UE 600, the non-CSG UE 600 is connected to the neighbor NB
630 in order to receive service from the neighbor NB 630 by
performing a general handover procedure in step 629.
FIG. 7 is a signal flow illustrating a management method for
determining, by a NB, an access mode of the NB, and reporting the
access mode to a CN in a wireless communication system according to
an embodiment of the present invention.
Referring to FIG. 7, a NB 710 determines its own access mode in
step 710, and reports the determined access mode by transmitting an
access mode change request message to a CN 720 in step 703.
In step 705, the CN 720 controls the access mode of the NB 710.
Specifically, when the CN 720 has an allowance authority regarding
the access mode decision, the CN 720 may determine whether to allow
the access mode decision or determine a different access mode and
allocate a suitable PCI through a separate access mode decision
algorithm. However, when the CN 720 does not have the allowance
authority regarding the access mode decision, the CN 720 may
unconditionally determine an allowance with respect to the access
mode decision, and allocate a suitable PCI.
In step 707, the CN 720 transmits an access mode change response
message including an access mode control result to the NB 710. When
the CN 720 determines an allowance with respect to the access mode
decision of the NB 710 through the access mode control, the NB 710
transmits a system info.-message including system information of
the determined access mode to a UE 700 in step 709.
The UE 700 generates a measurement report message based on the
system info.-message received from the NB 710, and transmits the
measurement report message to the serving NB to try a handover to
the NB 710 or perform an initial access procedure to the NB 710 in
step 711.
FIG. 8 is a signal flow illustrating a management method for
determining, by a CN, an access mode of an NB and reporting the
access mode to the NB in a wireless communication system, according
to an embodiment of the present invention.
Referring to FIG. 8, when an NB 810 is installed or is powered on
in step 801, the NB 810 transmits a power-on-report message to a CN
820 in step 803.
The CN 820 controls an access mode of the NB 810 in step 805.
Specifically, the CN 820 determines the access mode of the NB 810
through a separate access mode decision algorithm, and allocates a
suitable PCI. The CN 820 transmits an access mode change response
message including an access mode control result to the NB 810 in
step 807.
In step 809, the NB 810 transmits a system info.-message including
system information of the determined access mode to a UE 800.
The UE 800 generates a measurement report message based on the
system info.-message received from the NB 800, and transmits the
measurement report message to the serving NB to try a handover to
the NB 810 or to perform an initial access procedure to the NB 810
in step 811.
FIG. 9 is a signal flow illustrating a management method for
requesting, by a neighbor NB, an NB to change an access mode for
the purpose of reducing an inter-cell interference in a wireless
communication system according to an embodiment of the present
invention.
Referring to FIG. 9, a UE 900 is connected to a serving NB 920 to
receive a service from the serving NB 920 in step 901.
A neighbor NB 910 of the UE 900 determines to request a peripheral
NB to change an access mode for the purpose of reducing an
inter-cell interference in step 903. For example, the neighbor NB
910 may requests the serving NB 920 to change its access mode. The
following description is described using the above example.
In step 905, the neighbor NB 910 transmits an access mode change
request message to a CN 930. Here, the access mode change request
message requests the serving NB 920 to change the access mode.
The CN 930 controls the access mode of the serving NB 920 in step
907. Specifically, when the CN 930 has an allowance authority
regarding the access mode change, the CN 930 may determine whether
to allow the access mode change through a separate access mode
change algorithm. However, when the CN 930 does not have the
allowance authority regarding the access mode change, the CN 930
may unconditionally determine allowance with respect to the access
mode change.
When determining to allow the access mode change of the serving NB
920, the CN 930 transfers the access mode change request message to
the serving NB 920 in step 909.
The serving NB 920 that has received the access mode change request
message controls its own access mode in step 911. That is, the
serving NB 920 determines whether to allow its access mode to
change.
When the serving NB 920 is a femto NB, the serving NB 920 may
additionally receive an allowance from an owner of the femto NB to
change the access mode.
In step 913, the serving NB 920 transmits an access mode change
response message including an access mode control result to the CN
930, and in step 917, the CN 930 transfers the access mode change
response message including the final access mode control result to
the neighbor NB 910.
When determining to allow the access mode change of the serving NB
920, the serving NB 920 in forms the UE 900 that the access mode
has changed, and accordingly, that the system information has
changed, by transmitting a system information modification message
to the UE 900 in step 915. In addition, the serving NB 920 may
transmit a changed system info.-message including system
information of the changed access mode to the UE 900 in step
919.
In conjunction with FIG. 9, the transfer of the access mode change
request message has been described using an example in which the
neighbor NB 910 transfers the access mode change request message to
the serving NB 920 via the CN 930. However, when direct
communication, such as an X2 interface between NBs is possible, the
neighbor NB 910 may directly transfer the access mode change
request message to the serving NB 920, which will be described in
more detail with reference to FIG. 10.
FIG. 10 is a signal flow illustrating a management method for
requesting, by a neighbor NB, an NB to change an access mode for
the purpose of reducing an inter-cell interference in a wireless
communication system according to an embodiment of the present
invention.
Referring to FIG. 10, a UE 1000 is connected to a serving NB 1020
to receive a service from the serving NB 1020 in step 1001.
A neighbor NB 1010 of the UE 1000 may determine to request a
peripheral NB to change an access mode for the purpose of reducing
an inter-cell interference in step 1003. For example, the neighbor
NB may request the serving NB 1020 to change its access mode. The
following description is made using the above example.
The neighbor NB 1010 transmits an access mode change request
message to the serving NB 1020 in step 1005. Here, the access mode
change request message requests the serving NB 1020 to change the
access mode.
In step 1007, the serving NB 1020 controls its own access mode.
That is, the serving NB 1020 determines whether to allow its access
mode to change.
When the serving NB 1020 is a femto NB, the serving NB may
additionally receive an allowance from an owner of the femto NB to
change the access mode.
When determining to allow its access mode change, the serving NB
1020 transfers the access mode change request message to a CN 1030
in step 1009.
The CN 1030 that has received the access mode change request
message controls the access mode of the serving NB 1020 in step
1011. Specifically, when the CN 1030 has an allowance authority
regarding the access mode change, the CN 1030 may determine whether
to allow the access mode change through a separate access mode
change algorithm. However, when the CN 1030 does not have the
allowance authority regarding the access mode change, the CN 1030
may unconditionally determine allowance with respect to the access
mode change.
The CN 1030 transmits an access mode change response message
including an access mode control result to the serving NB 1020 in
step 1013. The serving NB 1020 transfers the access mode change
response message including the final access mode control result to
the neighbor NB 1010 in step 1015.
Alternatively, instead of the two messages in steps 1013 and 1015,
the CN 1030 may directly transfer the access mode change response
message including the access mode control result to the neighbor NB
1010.
When determining to allow its access mode change, the serving NB
1020 informs the UE 1000 that the access mode has changed, and
accordingly, that system information has changed, by transmitting a
system information modification message to the UE 1000 in step
1017. In addition, the serving NB 1020 may transmit a system
info.-message including system information of the changed access
mode to the UE 1000 in step 1019.
Table 1 summarizes an operating method of an NB according to an
access mode change of the NB.
TABLE-US-00001 TABLE 1 changing existing Closed Hybrid Open Closed
-- treats existing it is possible in the CSG UE case where there
considerately is not CSG UE (case 3) (case 5) Hybrid commands open
-- it is possible in the user to handover case where there (case 1)
is not CSG UE (case 6) Open commands open treats existing -- user
to handover CSG UE (case 2) considerately, and commands open user
to handover depending on a resource shortage (case 4)
Referring to Table 1, when an access mode change occurs, an NB
notifies a system information change to a UE communicating with the
NB in a previous access mode. Of course, in cases of cases 1 and 2
above, which allow all UEs that operate in a previous access mode
to perform a handover, such a system information change notice is
not required.
In cases 3 and 5, when an NB that is requested to change an access
mode is a femto NB, receiving an allowance from an owner of the
femto NB to change the access mode may be additionally
performed.
FIG. 1 is a signal flow illustrating an operating method for cases
1 and 2 of Table 1, for changing an access mode of an NB from a
hybrid access mode or an open access mode to a closed access mode
in a wireless communication system according to an embodiment of
the present invention.
Referring to FIG. 11, a non-CSG UE 1100 is connected to an open or
hybrid NB 1120 as an open user to receive a service in step 1101.
In step 1103, the non-CSG UE 1100 receives hybrid/open access
system info.-message transmitted by a serving NB 1120 of the
non-CSG UE 1100.
In step 1105, the NB 1120 may determine to change its access mode
to a closed access mode. When determining to change its access
mode, the NB 1120 reports the access mode change to a CN 1130 by
transmitting an access mode change request message to the CN 1130
in step 1107.
In step 1109, the CN 1130 controls the access mode of the NB 1120.
Specifically, when the CN 1130 has an allowance authority regarding
the access mode decision, the CN 1130 may determine whether to
allow the access mode decision or determine a different access mode
and allocate a suitable PCI through a separate access mode decision
algorithm. However, when the CN 1130 does not have the allowance
authority regarding the access mode decision, the CN 1130 may
unconditionally determine an allowance with respect to the access
mode decision, and allocate a suitable PCI.
The CN 1130 transmits an access mode change response message
including an access mode control result to the NB 1120 in step
1111. When the CN 1130 determines to allow the access mode decision
of the NB 1120, the NB 1120 orders the non-CSG UE 1100 to perform a
handover in step 1113, and transmits a closed access system
info.-message including system information of the determined
changed access mode to the CSG UE 1110 in step 1115.
The CSG UE 1110 generates a measurement report message based on the
system info.-message received from the NB 1120, and transmits the
measurement report message to the serving NB to try a handover to
the NB 1120 or perform an initial access procedure to the NB 1120
in step 1117. In step 1119, the CSG UE 1110 is connected to the NB
1120, now in the closed access mode, to receive service.
FIG. 12 is a signal flow illustrating an operating method for case
3 of Table 1, for changing an access mode of an NB from a closed
access mode to a hybrid access mode in a wireless communication
system according to an embodiment of the present invention.
Referring to FIG. 12, a CSG UE 1210 is connected to a closed NB
(serving NB) 1220 as a closed user to receive service in step 1201.
In step 1203, the CSG UE 1210 receives a closed access system
info.-message transmitted by the serving NB 1220.
The NB 1220 may determine to change its access mode from a closed
access mode to a hybrid access mode in step 1205. When determining
to change its access mode, the NB 1220 transmits an access mode
change request message to the CN 1230 in step 1207.
In step 1209, the CN 1230 controls the access mode of the NB 1220.
Specifically, when the CN 1230 has an allowance authority regarding
the access mode decision, the CN 1230 may determine whether to
allow the access mode decision or determine a different access mode
and allocate a suitable PCI through a separate access mode decision
algorithm. However, when the CN 1230 does not have the allowance
authority regarding the access mode decision, the CN 1230 may
unconditionally determine an allowance with respect to the access
mode decision, and allocate a suitable PCI.
In step 1211, the CN 1230 transmits an access mode change response
message including an access mode control result to the NB 1220.
When the CN 1230 determines to allow the access mode decision of
the NB 1220, the NB 1220 informs the CSG UE 1210 that the access
mode has changed, and accordingly, that system information has
changed, by transmitting a system information modification message
to the CSG UE 1210 in step 1213. In addition, the NB 1220 transmits
a hybrid access system info.-message including system information
of the changed access mode to the CSG UE 1210 and a non-CSG UE 1200
in steps 1215 and 1217, respectively.
In step 1219, the non-CSG UE 1200 generates a measurement report
message based on the system information message received from the
NB 1220, and transmits the measurement report message to the
serving NB to try a handover to the NB 1220 or perform an initial
access procedure to the NB 1220. In step 1221, the non-CSG UE 1200
is connected to the NB 1220 of the hybrid access mode as an open
user to receive service.
In FIG. 12, when the NB 1220 is a femto NB, the NB may additionally
receive an allowance from an owner of the femto NB to change the
access mode. That is, as illustrated in FIG. 13, when determining
to change its access mode from a closed access mode to a hybrid
access mode in step 1305, an NB 1320 may additionally transmit an
access mode change request message to the owner 1310 of the femto
NB in step 1307, and receives an access mode change response
message from the owner 1310 of the femto NB in step 1309. Because
the remaining steps in FIG. 13, i.e., Steps 1301, 1303, and
1311-1325, are the same as those of FIG. 12, a repetitive detailed
description thereof is omitted.
Though description has been made using an example where an NB
requests a CN to change its access mode with reference to FIGS. 12
and 13, the CN may request the NB to change its access mode, which
will be described in more detail with reference to FIG. 14.
FIG. 14 is a signal flow illustrating an operating method for case
3 in Table, for changing an access mode of an NB from a closed
access mode to a hybrid access mode in a wireless communication
system according to an embodiment of the present invention.
Referring to FIG. 14, a CSG UE 1410 is connected to a closed NB
(serving NB) 1420 as a closed user to receive service in step 1401.
In step 1403, the CSG UE 1410 receives a closed access system
info.-message transmitted by the serving NB 1420 of the CSG UE
1410.
A CN 1430 may determine to change the access mode of the NB 1420
from the closed access mode to a hybrid access mode in step 1405.
When determining to change the access mode of the NB 1420, the CN
1430 requests the NB 1420 to change the access mode by transmitting
an access mode change request message to the NB 1420 in step
1407.
When the NB 1420 is a femto NB, the NB 1420 may additionally
receive an allowance from an owner of the femto NB to change the
access mode. That is, the NB 1420 may additionally transmit an
access mode change request message to the owner 1410 of the femto
NB in step 1409, and receive an access mode change response message
from the owner 1410 of the femto NB in step 1411.
The NB 1420 transmits an access mode change response message
including an access mode change response to the CN 1430 in step
1413. When the owner 1410 of the femto NB allows the access mode
change, the NB 1420 informs the CSG UE 1410 that the access mode
has changed, and accordingly, that system information has changed,
by transmitting a system information modification message to the
CSG UE 1410 in step 1415. In addition, the NB 1420 transmits a
hybrid access system info.-message including system information of
the changed access mode to the CSG UE 1410 and a non-CSG UE 1400 in
steps 1417 and 1419, respectively.
In step 1421, the non-CSG UE 1400 generates a measurement report
message based on the system information message received from the
NB 1420, and transmits the measurement report message to the
serving NB to try a handover to the NB 1420 or perform an initial
access procedure to the NB 1420. In step 1423, the non-CSG UE 1400
is connected to the NB 1420, now operating in the hybrid access
mode, as an open user to receive service.
FIG. 15 is a signal flow illustrating an operating method for case
4 of Table 1, for changing an access mode of an NB from an open
access mode to a hybrid access mode in a wireless communication
system according to an embodiment of the present invention.
Referring to FIG. 15, a non-CSG UE 1500 is connected to an open NB
(serving NB) 1520 as an open user to receive service in step 1501.
In step 1503, the non-CSG UE 1500 receives an open access system
info.-message transmitted by the serving NB 1520.
The NB 1520 may determine to change its access mode to a hybrid
access mode in step 1505. When determining to change its access
mode, the NB 1520 transmits an access mode change request message
to the CN 1530 in step 1507.
In step 1509, the CN 1530 controls an access mode of the NB 1520.
Specifically, when the CN 1530 has an allowance authority regarding
the access mode decision, the CN 1530 may determine whether to
allow the access mode decision or determine a different access mode
and allocate a suitable PCI through a separate access mode decision
algorithm. However, when the CN 1530 does not have the allowance
authority regarding the access mode decision, the CN 1530 may
unconditionally determine an allowance with respect to the access
mode decision, and allocate a suitable PCI.
In step 1511, the CN 1530 transmits an access mode change response
message including an access mode control result to the NB 1520.
When the CN 1530 determines an allowance with respect to the access
mode decision of the NB 1520, the NB 1520 may determine a handover
of the non-CSG UE 1500 depending on a resource shortage in step
1513. In addition, the NB 1520 informs the non-CSG UE 1500 that the
access mode has changed, and accordingly, that system information
has changed, by transmitting a system information modification
message to the non-CSG UE 1500 in step 1515. In addition, the NB
1520 transmits a hybrid access system info.-message including
system information of the changed access mode to the non-CSG UE
1500 and a CSG UE 1510 in steps 1517 and 1519, respectively.
In step 1521, the CSG UE 1510 generates a measurement report
message based on the system information message received from the
NB 1520, and transmits the measurement report message to the
serving NB to try a handover to the NB 1520 or perform an initial
access procedure to the NB 1520. In step 1523, the CSG UE 1510 is
connected to the NB 1520, now operating in the hybrid access mode,
as a closed user to receive a service.
Because cases 5 and 6 are the same as the foregoing, repetitive
detailed descriptions thereof are omitted.
FIG. 16 is a flowchart illustrating an operating method of an NB,
for changing an access mode of a neighbor NB according to a request
of the NB in a wireless communication system according to an
embodiment of the present invention.
Referring to FIG. 16, the NB determines to change an access mode of
a neighbor NB for the purpose of reducing interference or
distributing a cell load in step 1601. In step 1603, the NB
transmits, to a CN or directly to the neighbor NB, an access mode
change request message requesting the neighbor NB to change the
access mode, and in step 1605, receives an access mode change
response message including an access mode control result from the
CN or the neighbor NB.
FIG. 17 is a flowchart illustrating an operating method of a
neighbor NB, for changing its access mode according to a request of
an NB in a wireless communication system, according to an
embodiment of the present invention.
Referring to FIG. 17, in step 1701, a neighbor NB determines
whether an access mode change request message requesting the
neighbor NB to change an access mode is received from a CN or
directly from an NB.
When the access mode change request message requesting the neighbor
NB to change the access mode is received from the CN or directly
from the NB, the neighbor NB controls its access mode in step 1703.
That is, the neighbor NB determines whether to allow its access
mode to change.
When the neighbor NB is a femto NB, the neighbor NB may
additionally receive an allowance from an owner of the femto NB to
change the access mode. In addition, the neighbor NB may transfer
the access mode change request message to the CN, receive an access
mode change response message including an access mode control
result from the CN, and finally determine whether to allow the
access mode change of itself based on an access mode control result
performed by the CN and an access mode control result performed by
the neighbor NB.
The neighbor NB transmits an access mode change response message
including a final access mode control result to the CN or the NB in
step 1705.
The neighbor NB determines whether an allowance has been determined
with respect to the access mode change of the neighbor NB as a
final access mode control result in step 1707.
When the access mode change of the neighbor NB is not allowed in
step 1707, the neighbor NB ends the procedure.
However, when the access mode change of the neighbor NB is allowed
in step 1707, the neighbor NB informs a UE that the access mode has
changed, and accordingly, that system information has changed, by
transmitting a system information modification message to the UE in
step 1709. In step 1711, the neighbor NB transmits a system
information message including system information of the changed
access mode to the UE.
FIG. 18 is a flowchart illustrating an operating method of an NB,
for changing an access mode of the NB according to a request of the
NB in a wireless communication system, according to an embodiment
of the present invention.
Referring to FIG. 18, the NB determines to change its own access
mode in step 1801. When the NB is a femto NB, the NB may
additionally receive an allowance from an owner of the femto NB to
change the access mode.
In step 1803, the NB transmits an access mode change request
message to a CN, requesting to change its access mode, and in step
1805, receives an access mode change response message including an
access mode control result from the CN.
The NB determines whether an allowance has been determined with
respect to the access mode change of the NB as an access mode
control result in step 1807.
When the access mode change of the NB has not been allowed in step
1807, the NB ends the procedure.
However, when the access mode change of the NB has been allowed in
step 1807, the NB informs a UE that the access mode has changed,
and accordingly, that system information has changed, by
transmitting a system information modification message to the UE in
step 1809. In step 1811, the NB transmits a system information
message including system information of the changed access mode to
the UE.
FIG. 19 is a block diagram illustrating an NB according to an
embodiment of the present invention.
Referring to FIG. 19, the NB includes a duplexer 1901, a reception
modem 1903, a message processor 1905, a controller 1907, an access
mode change unit 1909, a message generator 1911, and a transmission
modem 1913.
The duplexer 1901 transmits a transmission signal provided from the
transmission modem 1913 via an antenna, and provides a reception
signal from the antenna to the reception modem 1903 according to a
duplexing scheme.
The reception modem 1903 recovers data from a signal provided from
the duplexer 1901, and transfers the data to the message processor
1905. For example, the reception modem 1903 includes a Radio
Frequency (RF) reception block, a demodulation block, and a
channel-decoding block. The RF reception block includes a filter
and an RF pre-processor. When a wireless communication system
utilizes OFDM scheme, the demodulation block includes a Fast
Fourier Transform (FFT) operator for extracting data contained in
each subcarrier. The channel-decoding block includes a demodulator,
a deinterleaver, and a channel decoder.
The message processor 1905 extracts control information from a
signal provided from the reception modem 1903 and provides the
extracted control information to the controller 1907. For example,
the message processor 1905 extracts a message related to an access
mode change provided from a CN or a neighbor NB, and provides the
extracted message to the controller 1907.
The controller 1907 controls an entire transmission/reception
operation of the NB. Specifically, the controller 1907 determines
to change an access mode of a neighbor NB or the NB for the purpose
of reducing an interference or distributing a cell load, controls
the message generator 1911 to generate an access mode change
request message requesting the access mode change according to the
decision, and controls the transmission modem 1913 to transmit the
generated message to the CN or the neighbor NB. In addition, when
an access mode change request message requesting the NB to change
the access mode of the NB is received from the CN or the neighbor
NB via the message processor 1905, the controller 1907 controls the
access mode of the NB to determine whether to allow the access mode
change of the NB, controls the message generator 1911 to generate
an access mode change response message including an access mode
control result according to the decision, and controls the
transmission modem 1913 to transmit the generated message to the CN
or the neighbor NB.
When the NB is a femto NB, the controller 1907 may additionally
receive an allowance from an owner of the femto NB to change the
access mode. In addition, when determining to change the access
mode of the NB or performing an access mode control in response to
a request of the CN or the neighbor NB to allow the access mode
change of the NB, the controller 1907 controls the message
generator 1911 to generate a system information modification
message informing that the access mode has changed, and
accordingly, that system information has changed, and generate a
system information message including system information of the
changed access mode, and controls the transmission modem 1913 to
transmit the generated messages to the UE.
The access mode change unit 1909 changes the access mode of the NB
according to the decision of the controller 1907.
The message generator 1911 generates a message to be transmitted to
the CN, the neighbor NB, or the UE under control of the controller
1907, and provides the generated message to the transmission modem
1913. For example, the message generator 1911 generates a message
related to the access mode change and provides the same to the
transmission modem 1913.
The transmission modem 1913 converts a message or transmission data
provided from the message generator 1911 into a form for
transmission via a radio resource and provides the same to the
duplexer 1901. For example, the transmission modem 1913 includes a
channel encoding block, a modulation block, and an RF transmission
block. The channel encoding block includes a modulator, an
interleaver, and a channel encoder. When a wireless communication
system utilizes the OFDM scheme, the modulation block includes an
Inverse Fast Fourier Transform (IFFT) operator for mapping data to
each subcarrier. The RF transmission block includes a filter and an
RF pre-processor.
In the above description of FIG. 19, the controller 1907 controls
the message processor 1905, the access mode change unit 1909, and
the message generator 1911. Alternatively, the controller 1907 may
perform the functions of the message processor 1905, the access
mode change unit 1909, and the message generator 1911. The separate
configuration and illustration of the controller 1907 controls the
message processor 1905, the access mode change unit 1909, and the
message generator 1911 in FIG. 19 is provided for separately
describing each function. Therefore, in actual realization, all or
some of the functions of them may be processed by the controller
1907.
As described above, the various embodiments of the present
invention solve an interference problem generated between neighbor
NBs that use different access modes, while using the same
frequency, and provide a load balancing effect in a specific area
or when an event occurs by changing an access mode of an NB
depending on different factors in a wireless communication
system.
While the present invention has been shown and described with
reference to certain embodiments thereof, it will be understood by
those skilled in the art that various changes in form and details
may be made therein without departing from the spirit and scope of
the present invention as defined by the appended claims and their
equivalents.
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